Conventionally, a navigation apparatus which detects the current position of a vehicle equipped with the navigation apparatus using GPS (Global Positioning System), detects the traveling direction of the vehicle using a gyro sensor, reads map data about an area surrounding the current position of the vehicle from a storage medium so as to form a map, displays the map on a display screen, and displays the current position and traveling direction of the vehicle on this map is known.
As such a navigation apparatus, for example, a navigation apparatus which updates map data stored in a hard disk drive unit (referred to as “HDD (Hard Disk Drive)” from here on) using map update information stored in a DVD-ROM (DVD-Read Only Memory) mounted to a DVD (Digital Versatile Disk) drive is known. This navigation apparatus writes map data read from the DVD-ROM in the HDD first. After that, the navigation apparatus carries out various processes by reading the map data from the HDD at a high speed and by writing certain data in the HDD. Therefore, this prior art navigation apparatus can reduce the time required to carry out a display of a map and route searching as compared with a case in which map data are read directly from the DVD-ROM and are processed.
However, because the above-mentioned prior art navigation apparatus can freely write map data read from a DVD-ROM in an HDD, it can also allow map data stored in a single DVD-ROM to be copied illegally into a large number of HDDs. Therefore, a navigation apparatus which prevents the use of map data copied illegally has been developed (for example, refer to patent reference 1).
This navigation apparatus is provided with a first data recording unit for mounting a first storage medium (concretely, a DVD-ROM which stores map update information), a second data recording unit for mounting a second storage medium (concretely, an HDD which stores map data), a data decision processing means for judging whether or not data are included in the first storage medium, and a data selection processing means for, when data are included in the first storage medium, selecting one of data stored in the first storage medium and data stored in the second storage medium, and for, when no data are included in the first storage medium, stopping the selection of data. Because this navigation apparatus stops the selection of data when no data are included in the first storage medium, it can prevent the use of data copied illegally.
[Patent reference 1] JP, 2003-216504, A
Because the navigation apparatus disclosed by above-mentioned patent reference 1 stops reading of map data from the second storage medium when the first storage medium is not mounted and then inhibits the output of all information which the navigation apparatus can provide for the user, the navigation apparatus can prevent any illegal use of the map information.
A problem is, however, that when the first storage medium is not mounted and the navigation apparatus then inhibits the output of all the information which the navigation apparatus can provide for the user, the user cannot judge whether the cause of the stop of the output of all the information is a failure of the navigation apparatus or another factor, and therefore the prior art navigation apparatus is inferior in user-friendliness.
The present invention is made in order to solve the above-mentioned problem, and it is therefore an object of the present invention to provide a user-friendly navigation apparatus which can make the user guess that the suppression of information which can be provided for the user results from illegal use of the map data.